ISO 21968-2019 PDF

Full title and description

ISO 21968:2019 — Non-magnetic metallic coatings on metallic and non‑metallic basis materials — Measurement of coating thickness — Phase‑sensitive eddy‑current method. This International Standard specifies a phase‑sensitive eddy‑current technique for non‑destructive measurement of the thickness of non‑magnetic metallic coatings applied to metallic and non‑metallic substrates.

Abstract

The standard defines how to use phase‑sensitive eddy‑current instruments to measure coating thickness on items such as zinc, cadmium, copper, tin or chromium on steel, and copper or silver on composite materials. The phase‑sensitive method is particularly suited to small surface areas and strong curvatures and is less affected by the magnetic properties of the base material than amplitude‑sensitive eddy‑current techniques; however, it is more sensitive to the electrical properties of the coating. The document also explains limitations that arise when the product of conductivity and permeability of coating and substrate differ by less than a factor of two.

General information

• Status: Published (International Standard, confirmed).
• Publication date: 19 September 2019.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 25.220.40 (metallic and other inorganic coatings).
• Edition / version: Edition 2 (2019).
• Number of pages: 39 (typical PDF edition page count).

Scope

ISO 21968:2019 specifies a non‑destructive, phase‑sensitive eddy‑current method for measuring the thickness of non‑magnetic metallic coatings on both metallic and non‑metallic basis materials. It covers a range of coating/base combinations commonly encountered in industry, including electroplated metallic layers and metallic coatings on composites, and describes applicability limits (notably when the product of conductivity and permeability for coating and substrate differs by less than two). The standard complements amplitude‑sensitive eddy‑current methods (for example ISO 2360) by enabling measurements on smaller or more strongly curved surfaces.

Key topics and requirements

• Principles and instrument requirements for phase‑sensitive eddy‑current measurement.
• Calibration procedures and reference standards for coating thickness measurement.
• Recommended measurement techniques for curved and small surface areas.
• Material applicability: examples include zinc, cadmium, copper, tin, chromium on steel and copper or silver on composites.
• Limits and uncertainty causes related to electrical conductivity and magnetic permeability of coating and substrate.
• Reporting and interpretation of measurement results for quality control and compliance.

Typical use and users

Used by quality and inspection laboratories, coatings and electroplating manufacturers, metallurgical test houses, automotive and aerospace component suppliers, instrument manufacturers (eddy‑current device makers), and certification bodies to verify coating thickness, ensure process control and compliance with procurement or regulatory requirements.

Related standards

Closely related to ISO 2360 (eddy‑current measurement — amplitude‑sensitive method) and earlier edition ISO 21968:2005 (withdrawn). National/adopted editions include regional adaptations such as BS EN ISO 21968:2019 and equivalent national publications. Relevant ISO/TC 107 committee publications and guidance on coating measurement practices provide complementary material.

Keywords

coating thickness; eddy‑current; phase‑sensitive; non‑destructive testing; metallic coatings; electroplating; measurement uncertainty; ISO 21968; ISO/TC 107.

FAQ

Q: What is this standard?

A: ISO 21968:2019 is an International Standard that specifies a phase‑sensitive eddy‑current method for non‑destructive measurement of the thickness of non‑magnetic metallic coatings on metallic and non‑metallic substrates.

Q: What does it cover?

A: It covers the use of phase‑sensitive eddy‑current instruments, calibration and measurement procedures, typical coating/base material combinations (e.g., zinc, cadmium, copper, tin, chromium on steel; copper or silver on composites), limitations and sources of measurement uncertainty, and reporting of results.

Q: Who typically uses it?

A: Coatings and electroplating manufacturers, inspection and testing laboratories, component manufacturers in sectors such as automotive and aerospace, instrument suppliers and conformity assessment bodies.

Q: Is it current or superseded?

A: The 2019 edition (Edition 2) is the current published edition (revises the 2005 edition). National adoptions (for example certain EN/BS/UNE versions) exist that correspond to the ISO text.

Q: Is it part of a series?

A: It is part of the body of standards dealing with coating measurement and testing under ISO/TC 107; related methods include amplitude‑sensitive eddy‑current measurement standards such as ISO 2360 and other sector or regional measurement standards.

Q: What are the key keywords?

A: Phase‑sensitive eddy‑current, coating thickness, non‑destructive testing, metallic coatings, electroplating, ISO 21968:2019, measurement uncertainty.